1. Field of the Invention
This invention is related to the cleaning of surfaces using the hydroblasting technique where the surface to he cleaned is exposed to a cleaning fluid mixture of liquid and abrasives which is ejected under high pressure. More particularly this invention is related to hydroblasting apparatus and methods which do not require the direct pumping of the abrasive component of the cleaning fluid mixture thereby greatly increasing, the operating life of the high pressure hydroblasting pump.
2. Description of Ralated Art
Many techniques have been used to clean surfaces by exposing the surfaces to abrasives ejected under high pressure. The abrasive particles can be ejected directly upon the surface to he cleaned, or can be injected in a slurry or "carrier" liquid such as water or other suitable liquid.
Sandblasting has been used for a number of years as a method for cleaning certain types of surfaces. Sandblasting involves the ejection of sand particles at high pressure. These ejected particles impinge upon the surface to be cleaned and the abrasive properties of the sand clean the struck surface. Sandblasting involves the direct injection of the abrasive sand particles. No carries liquid is used. Sandblasting results in the accumulation of material in the vicinity of the cleaning operation which consists of material removed from the cleaned surface as well as the ejected sand particles. Sandblasting is, therefore, an appropriate cleaning method when the accumulation of material is not critical. As an example, sandblasting is an appropriate method for cleaning flat exterior surfaces where accumulated material can be easily removed. Sandblasting is not, however, an appropriate method for cleaning the interior of pipes, conduits, valves and other internal surfaces where the accumulation of material can further clog the apparatus being cleaned. In addition, sandblasting may often pit or otherwise damage the surface being cleaned.
Another technique employed for cleaning various surfaces is a technique generally referred to as "hydroblasting". Hydroblasting uses a liquid which is typically water and which is ejected under high pressure onto the surface to be cleaned. Hydroblasting is designed to clean many types of surfaces including interior surfaces. As an example, hydroblasting is often used to clean the interior of pipes and tubes in oil field equipment, in manufacturing operations, and in numerous additional applications. Hydroblasting essentially consists of the utilization of a pumping mechanism which causes the pressurized release, through an appropriate nozzle, of a stream of water.
Unfortunately, hydroblasters have generally proved to be ineffective in the cleaning of pipes which are clogged with viscous materials. Since the hydroblasting technique generally relics upon the rotation of the injector nozzle and relies upon the high pressure injection of water, it is common for hydroblasters to bog down in viscous materials within the pipe. Since the hydroblaster emits one stream of liquid for cleaning purposes, the clogging of the hydroblaster prevents the hydroblaster from properly rotating for the thorough cleaning of the pipe interior. As the hydroblaister encounters obstructions within the pipe, the high pressure stream of liquid emitted from the hydroblaster will only clean in one azimuthal direction within the pipe. This results in azimuthal sectors of the pipe interior from which the viscous material has not been cleaned. This partial cleaning of the pipe interior is often referred to as "streaking".
It has been found that the sticking of pipes in an ineffective solution to the problem of clogged pipes. Whenever streaking occurs in a pipe, this results in easier and quicker accumulation of clogging material. Stated another way, streaking promotes additional accumulation of material or "addition". Since the use of conventional hydroblasters almost always results in the streaking of the interior conduit surface, hydroblasting is a relatively ineffective means for cleaning pipes and tubes, especially if these conduits are clogged with viscous material.
In conventional hydroblasting applications, when the hydroblasting nozzle becomes clogged within the pipe, the operator of the hydroblaster typically increases the pressure from the nozzle until it effectively penetrates the viscous material in the pipe. Under these circumstances, there is no way to maintain constant rotation of the spinning nozzle. As a result, it has become conventional in hydroblasting to rely on pure water force for the cleaning of pipes and other surfaces. The use of high pressure results in increased fuel consumption by the pumping mechanism. It also causes an increase in fatigue of the blaster gunner. As increased fatigue is applied to all components of the hydroblasting apparatus, there is a corresponding increase in the chance of an accident resulting form component failure under high pressure. Given the high pressures that are utilized in any hydroblasting operation, any metal fatigue or other material deterioration can cause a potentially fatal accident. In order to avoid such fatigue and dangers, hydroblasting companies must greatly increase their costs of maintenance and inspection of equipment. Another problem associated with the use of extremely high pressures for the hydroblasting of surfaces is that higher pressures more frequently result in lower amounts of water ejected per unit time, or lower "blasting volumes". Reduction in blasting volume usually results in less waste product removal from the surface being cleaned.
U.S. Pat. No. 5,375,378 to James J. Rooney. which is assigned to the assignee of the present disclosure, discloses a solution which greatly improves the hydroblasting technique. The teachings of this patent are herein entered by reference. In summary, Rooney discloses apparatus and methods for cleaning a surface which utilize a hydrolyzed solution of preferably silica compound and water having solid particles of silica compound. The silica compound and the water are pumped, using separate pumps, to an orifice. The hydrolyzed solution is formed and ejected thought the orifice at a pressure greater than 500 pounds per square inch (psi) thereby impinging the solid particles of silica compound onto the surface to be cleaned. The abrasive action of tile solid particles clean the surface, and the water component continuously flushes abrasive particles and waste removed from the cleaned surface. The technique is suited for cleaning interior and exterior surfaces, and overcomes the previously discussed problems associated with conventional hydroblasting. As mentioned previously, the silica compound is delivered to the nozzle by means of a dedicated pump. The abrasive silica compound greatly reduces the operating life of this dedicated pump. Presently, there is no known high pressure pump that will effectively pump the silica compound for an extended operating period. This requires that the pump be service finds maintained at frequent intervals thereby significantly increasing the cost of the cleaning operation.
An object of the present invention is to provide apparatus and methods for cleaning interior and exterior surfaces using a high pressure pumping mechanism, wherein the apparatus requires minimal maintenance, and wherein a hydrolyzed solution is delivered at high pressure but does not pass thorough the pumping mechanism.
An additional object of the present invention is to provide a cleaning technique which, when used to cleaning interior surfaces such as pipes or tubes, does not cause streaking.
A further object of the present invention is to provide a hydroblasting method for cleaning which reduces effective pressure required for effective cleaning.
A still further object of the present invention is to provide a cleaning apparatus which is optimized for vertical orientation and can be modified for horizontal orientations and wherein portions of the apparatus can be shut down for maintenance or repair without terminating cleaning operations.
Another object of the present invention is to provide a method for cleaning which is environmentally sale.
A further objective of the present invention is to provide apparatus and methods for controlling the temperature of the solution being nucleated thereby preventing temperature related nucleation retardation.
There are other objects and applications of the present invention which will become apparent in the following disclosure and claims.